Fix build on cc65 >= 2.18 (without breaking <= 2.17)

1 files changed, 20 insertions, 0 deletions

diff --git a/conio/mul40.s b/conio/mul40.s
new file mode 100644
index 0000000..99dd006
--- /dev/null
+++ b/conio/mul40.s
@@ -0,0 +1,20 @@
+; Compatibility wrapper for cc65's mul40 or _mul40 library routine.
+; Necessary because cc65 <= 2.17 has "mul40" as part of its atari
+; library, but 2.18 and up made it a C-callable routine on all
+; platforms, meaning its name grew a _ in front, "_mul40".
+
+; The .VERSION pseudo-variable is documented as "major version
+; times $100, plus minor version times $10". Whoever came up with
+; this design must have thought the minor version would never exceed
+; 15... starting with 2.16, the minor nybble overflows into the major
+; one, meaning cc65-2.17's .VERSION is actually $0310. Which is fine,
+; so long as there's never a cc65 major version 3.x (if this happens,
+; versions 3.0 and 3.1 will fail to build this correctly, then 3.2
+; will work again).
+
+.if .VERSION <= $0310 ; $0310 == 2.17
+  .import mul40
+.else
+  .import _mul40
+mul40 = _mul40
+.endif